Typical telescoping fluid actuators available in the art include telescoping piston/piston rods which are extendible responsive to fluid pressure acting on the piston for moving the piston and associated rod. However, once the telescoping piston/piston rods are displaced to an extended position, it was necessary to relieve the pressure on the piston by venting the cylinder and manually forcing the extended piston/piston rods back into their retracted positions in the cylinder. Alternatively, in order to retract the piston/piston rod assemblies back into the cylinder, long, flexible hoses have been mounted externally of the cylinder and in communication with the return side (face) of the pistons so that fluid pressure may be directed into the cylinder against the face of the pistons for displacing the piston/piston rod assemblies to its initial (unextended) position in the cylinder.
Both of these approaches have shortcomings. In the first case, once the piston/piston rod has been extended, it becomes a burdensome task for one to reach and manually exert an external force on the end of the extended piston rod while venting the cylinder. In the second case, which relies on the use of long flexible hoses which must move (extend) with each extending telescoping piston/piston assembly to provide the return fluid pressure, the fluid lines become entangled or at the very least pose a significant problem when the fluid cylinders are not used because they must be left to clutter up the space adjacent to the fluid actuators.
To overcome these noted difficulties, the applicant has provided a compact telescoping fluid actuator system which includes internal passageways which extend with the extending piston/piston rod assemblies while maintaining each face of the pistons in fluid communication with a source of fluid pressure without the need of extendible fluid lines.
It is, therefore, an object of the present invention to provide a telescoping fluid actuator system.
It is another object of the present invention to provide an internally ported fluid actuator system having plural telescoping piston/piston rod assemblies.
These and other objects of the present invention will become more readily apparent from the following description and accompanying drawings.